Coating



. cient length Patented "Oct. 30, 19 23. a

JOHN iANDREW DALY, OF NEW PAT aen wea January 22, was.

DENTURE PROCESS 00., INC., A CORPORATION OF I D COATING.

No Drawing. Application flled' llay 1, 1822, Serial No. 557,651.

To whom it mag camera:

Be it known that I, Joiriv A. DALY, a citizen of the Unitetf States,residing Rochelle Park, New Rochelle, in'the county of Westchester andState of New invented certain new and useful Improvements in Coating, ofwhich the following is a specification.

he invention relates to the coating of vulcanite or similar plates withmetals such as gold, silver platinum, tin, etc., and has as an object te application of a metal to a plate of such material so as to beinseparable therefrom.

further object of the invention is the placing of a coating of metalupon a plate of the nature mentioned in such a manner that the metalwill exist not only upon the surface df the plate but to a within thebody thereof. 1

To prepare the plate for the treatment b it is first thoroughly cleanedfrom any foreign matter, especially such as is of a greasy nature, andto this end may be immersed in or scrubbed with soda or lye. The plateis'then immersed in some substance which has the power of dissolving thevulcanite, as for instance chloroform, alcohol, acetic acid, or amixture thereof, and is allowed. to remain therein a sufiiof time forthe material of the plate upon its surface and for a slight depththerebelow to become, softened by the action of the solvent. This willusually take place in about twenty minutes.

The third step in the practice of the invention is the cleansing of theplate from p on.

the solvent, for which purpose it may be merely washed with water.

Fourth, the plate immediately after wash ing is placed in an aqueoussolution of gold chloride, silver nitrate, or a dissolved salt of themetal which is to be deposited-there- In the case of silver or goldabout a 20% solution is found to give good results. In the solution ofthe metallic salt about 10% of potassium solved and a reducing agent,such as oxalic or a 'tannic acid is added thereto.

The metallic salt in the presence of potassium sulphide and the reducingagent will The metal seems to have an affinity for the sub- York, have hslight extent b sulphide (K S) is dis ,metal is precipitated softenedsurface.

stances supplied to the rubber for its vulcamzation iii-such a in thesoluthe accomfresh metal thereon at each treatment, withoutan additionalbath in the vulcanite solvent. After sufficient metal has been depositedon the plate to make the surface thereof an electric metallic salt. I echemical reactions which take place in the carrying out of the inventionare very complex and difiicult of explanation. Apparently in thepresence of potassium sulphide a double sulphide of gold and potassiumis formed, which sulphide is reduced by the reducing agent with the.consequent precipitationof the metal upon and within the body oftheplate.

'nor changes may be made in the steps of the process without departingfrom the spirit of the invention.

claim:

1. The process of coating a body of vul canitewith metal which comprisessoftening the surface of the body by ch and causing a precipitation of ametal upon and below the softened surface of the body.

2. The process of coating a body of vulcanized rubber with a metal which.comprises softening the surface of the body by treatment with asolvent, immersing the ody in an aqueous solution of a salt of the metaland a .reducingagent, whereby the upon and below the The process ofcoating a body of vulcanized rubber which comprises cleansing the body,treating the surface thereof with a solvent until the material softenedto a slight depth,

removing the solvent, treating the body with an aqueous emical means ofthe body is ioo ' solution of a nletallic salt containing areexceedingly-finest'ete of subdlvisioh' is deducing agent, whereby :themetal in en ex posited upon end belovfthe'surfaee of the ceediqgly finestate of subdivision 1 s debody.

v posited upon and below the surface of the 5. Thehfoces's of'coatlhgahatdnom I metallic body with metal, which comprises.

body.

' 4,- Th'e roce'ss of coating e body of vul- .treatlxig the surface ofthe bodyto soften eaxiized rubber with metal which comprises the same we'sl-ight depth,depositin meteltreatingthe body with .a solvent untilthe,in anexoeecli gly 'fine state of sub iyision -sm'faeethereofissoftenecl to e'slight depth, uponend beneath the softenedsurface of 'iemoving thesolvent, immersing the thus thehodyto produce afilm structurally-intreated body' in an aqueous solution of 'aeorpora'tedwith and overlyihg the surface salt, of the .metel',"potassium sulphide, -and .of the body. A e 4 a. reducing agent wherebythe 'm'ettil in an JOHN ANDREW DALY.

